The present invention refers to an apparatus for the automatic orientation of tubular articles, such as stockings and the like, in which one end is thicker than the other.
It is known that in the manufacturing of pantyhose articles, two stockings are sewn together in correspondence of a cut line to form the relevant bodice. To this end, machines are used, commonly known as xe2x80x9cLINE CLOSERSxe2x80x9d, which allow feeding the stockings suitably oriented with respect to their support shapes and usually dial-like disposed in a circular carrousel structure. Similarly, for the sewing of stocking toes, machines are used, commonly known as xe2x80x9cTOE-CLOSERSxe2x80x9d, which also imply feeding the stockings suitably oriented with respect to their support tubes commonly provided on such machines.
In this field, a crucial requirement is the automatic supply of articles to these machines, which implies to operate the automatic, instantaneous detection of the articles and their correct positioning, especially when considering the case in which the articles need to be picked up from a collection site where they are piled up in bulk.
The document EP 521206 discloses an apparatus comprising a conduit with an inlet or feed section for the admission of articles, in which a detection unit is fitted for sensing the articles orientation by two photocells positioned from opposite sides with respect to a filter-valve. The articles, being picked up from a container by means of an aspirator bidirectionally movable between the same container and the inlet section of said conduit, are made to transit, in correspondence of the above mentioned detection unit, by an air flow generated by suitable pneumatic means and causing the articles under treatment to move along a path delimited by a plurality of conduits suitably connected to each other. The above filter-valve is so disposed as to delimit, when activated, a space which only the thinner end of the articlexe2x80x94that is, the one relevant to the toe portionxe2x80x94is able to go through, the end comprising the elastic hem being remarkably thicher and thus unable to cross said space. Accordingly, once the filter-valve is activated, if both the unit""s photocells detect the presence of textile material in correspondence of the respective optical axes, then the in-process article results oriented with its toe turned forward, that is, in the same direction as the one of the flow which has moved it along. On the contrary, if the presence of the textile material is sensed by only the photocell which is upstream of the filter-valve, then the end of article moving forward is that of the elastic hem, since this part of the article is unable to go through the space cleared by the valve. Following the step of detection of the current orientation of the article, the latter is disengaged by moving the filter-valve back to the retracted rest position, that is, by clearing the cross-section of the articles"" admission conduit. The controlled article is thereby free to follow, being entrained by the air flow purposely generated, one or the other of the two paths, delimited by conduits downstream of the unit, according to current orientation of same article. In this way, the articles exit from the apparatus with the same orientation all the time. The document (IT) FI/96/A/163 discloses an apparatus comprising a unit for detecting the current orientation of the incoming articles and means able to change the orientation thereof if it does not correspond to the intended one. Said detection unit comprises a filter-valve of a type previously indicated and a photocell located upstream thereof. The filter-valve and photocell in question are located within a main conduit in which the articles, being fed by means of an automatic arm which takes them out of a container or a heap in which they are collected in bulk, are suitably conveyed by an air flow generated by an aspirator. Also provided are ancillary conduits suitably connected to the main conduit. When the selecting valve is in active state, that is, ready to intercept articles coming from the inlet section of the main conduit, and the same photocell detects the presence of textile material in correspondence of its optical axis, the article under treatment results oriented with its toe turned forward, that is, with its portion comprising the elastic hem being retained by the filter-valve. On the contrary, if the photocell does not give any reading, the article results oriented in a direction opposite to the previous one. To allow the articles going out of the apparatus with the same orientation all the time, means are provided apt to engage the articles in the desired way, said means being activated when the orientation detected by the photocell upstream of the filter-valve does not correspond to the intended one.
The apparatuses above described have some drawbacks. One drawback lies in the fact that the articles may disengage spontaneously from the filter-valve when presenting themselves with their toe turned forward, thereby preventing an accurate reading by the control photocells, which in turn implies a faulty data-processing and a reduced reliability of the mechanism. A further drawback stems from the need of associating one or two photocells to the filter-valve and, therefore, relying almost completely the above detection on the accuracy and correct operation of same photocells which, accordingly, need a continuous maintenance. Moreover, the heavy constructional complexity of the means which operate the onrientation of the articles as required, contributes to increasing the manufacturing cost of same means while bringing about greater difficulties in carrying out routine and extra service.
The main object of the present invention is to overcome the said drawbacks.
This result has been achieved, according to the invention, by providing an apparatus and a method having the features indicated in the characterizing part of independent claims. Further characteristics being set forth in the dependent claims.
The present invention makes it is possible to achieve the orientation and unloading of the articles as required by using an apparatus simple to make, cost-effective, reliable, of reduced dimensions, easy to inspect and requiring a minor and simplified maintenance.